In addition to the rain, gusty winds produced numerous broken tree branches, downed power lines, and traffic control lights throughout the downtown Portland area on Saturday night. Late Sunday, we saw more reports of tree damage and power outages with the final strong storm moving inland.

Sustained winds of 50 to 60 mph were reported throughout the region, and 70 to 80 mph gusts were observed along the coasts and in the mountains of Oregon and Washington.

Forecast: Worst is Over With

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For the Pacific Northwest, the worst of the rain and wind is now over with since the strong frontal system has pushed inland across the region.

That said, periods of rain and mountain snow will linger Monday night into at least Tuesday, as pulses of energy rotate around the bullish upper-level jet stream dip into the Northwest.

Across the interior Northwest, from eastern Washington and eastern Oregon to Montana, Idaho and Wyoming, strong winds will continue into Monday.

How Unusual For September?

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We're in a transition zone between the summer dry season and the wet season of late fall and winter.

The jet stream eventually begins to aim at the Northwest more often in the fall. When this occurs, a succession of storms can march into the West Coast, delivering rain, wind, and mountain snow.

Excessive rain can occur when one storm taps a so-called atmospheric river of moisture originating from the subtropics, or, when a series of storms delivers moderate rainfall totals over a period of a week or more.

This was quite an exceptional storm for late September, as the NWS office in Portland, Ore. noted by leading off its Saturday morning forecast with "A rare major September storm system."

Prior to the rain ramping up Saturday, Seattle had already measured over three inches this month. As you can see in the graph above, an average September manages just under an inch and a half. Seattle picked up more than that from just Saturday's round of the weekend storm parade!